This application claims priority to Japanese Patent Application No. 2001-099763, filed on Mar. 30, 2001, which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to novel oil-in-water type emulsion foods, which exhibit excellent cold resistance (stability) such as refrigeration resistance (stability), freeze resistance (stability), or the like.
2. Discussion of the Background
In recent years, freeze-processed foods such as frozen foods, frozen vegetables and the like have been increasingly demanded. Accordingly, improved cold resistance such as refrigeration resistance, freeze resistance, or the like has been sought for dressings, mayonnaise, and spreads as well.
By the way, gelatin having food properties such as gelability, emulsifiability and the like is used as various foodstuffs, and also widely used as an emulsifier in dressings and mayonnaise.
For example, gelatin is added to an oil-in-water type emulsion food by a method using a modified gelatin obtained by heat treatment along with water and sugar (see Japanese Patent Kokai Publication JP-A-11-318,355). This method is, however, for imparting a heat resistance to an oil-in-water type emulsion food by preheating gelatin. No description or suggestion is found of imparting a freeze resistance therein.
As an approach for imparting a freeze resistance by adding gelatin to an oil-in-water type emulsion food, a large number of methods such as a method in which gelatin is blended with at least one of milk whey protein, caseinate, and a polyglycerin fatty acid ester (see Japanese Patent Kokai Publication JP-A-60-137,260); a method in which egg yolk is incorporated in an amount of 2% or more, milk protein in an amount of 0.5% by weight or more, and gelatin in an amount of 0.3% or more, and an amount of an oily phase is adjusted to 40% or less (see Japanese Patent Kokai Publication JP-A-9-149,772); a method in which appropriate amounts of gelatin and hydrolyzed starch are added to mayonnaise (see Japanese Patent Kokai Publication JP-A-49-26,439); and the like are known.
Since, however, gelatin is not examined and studied in detail in these methods, there is no description of the molecular weight of the gelatin or of the use of fish gelatin in these publications.
In this regard, Japanese Patent Kokai Publication JP-A-49-26,439 describes on page 2, left column, line 16 to right column, line 2 that xe2x80x9cHowever, in a product containing only gelatin added, remaining water unbound migrates onto a surface during the freezing (freeze-up), so that an ice layer is formed on the mayonnaise surface.xe2x80x9d Thus, it is understood that according to this method, an adequate freeze resistance cannot be imparted with the gelatin only. For this reason, there is a need to add a milk whey protein, a hydrolyzed starch and the like. As a result, this approach involves problems in that an unpleasant flavor or an unpleasant feel in the mouth, such as a rough feel, is provided.
As an attempt to impart a freeze resistance using fish gelatin, the prevention of water separation from a frozen food by mixing a fish gelatin powder to foodstuffs before coagulation (solidification) has been proposed (an agent for prevention of water separation using the fish gelatin; see Japanese Patent Kokai Publication JP-A-11-164,655). However, this method is limited to the prevention of water separation from foods or foodstuffs such as tofu (soybean curd), chawan-mushi (steamed egg custard), croquette, konnyaku (devil""s tongue jelly) and the like, and it does not focus on de-emulsification (destruction of emulsification) by separation between an aqueous phase and an oily phase, which is a problem encountered in freezing an oil-in-water type emulsion.
Thus, there remains a need for oil-in-water type emulsion foods which exhibit an improved cold resistance (stability to storage at low temperatures). There also remains a need for methods for preparing such foods.
Accordingly, it is one object of the present invention to provide an excellent oil-in-water type emulsion food which is markedly improved in cold resistance such as refrigeration resistance, freeze resistance, or the like, especially freeze resistance.
It is another object of the present invention to provide novel methods for preparing such foods.
It is another object of the present invention to provide novel methods for imparting improved cold resistance to oil-in-water emulsion type foods.
These and other objects, which will become apparent during the following detailed description, have been achieved by the present inventors"" discovery that the cold resistance, especially the freeze resistance, of an oil-in-water type emulsion is markedly improved by the presence of gelatin, in which the content of the gelatin ingredient(s) (fraction(s)), which have a molecular weight of 20,000 or less, is 13% by weight or less. This finding has led to the completion of the present invention.
That is, the present invention provides an oil-in-water type emulsion food, comprising gelatin, in which the gelatin comprises 13% by weight or less of ingredient(s) (a fraction; gelatin ingredient(s)) having a molecular weight of 20,000 or less. In other words, the amount of the gelatin fraction, which has a molecular weight of 20,000 or less, does not exceed 13% by weight of the total weight of the gelatin in the oil-in-water type emulsion food product.
As this gelatin, fish gelatin is preferable.
An oil-in-water type emulsion food, comprising 0.1 to 5.0% by weight of such a gelatin and 35 to 70% by weight of an oily phase is especially preferable in view of production and/or taste.